A quick and inexpensive way of making this type of furniture consists in constraining to a supporting structure one or more supporting elements, with which the portion of structure intended to support the weight of the person, for example the seat or backrest for chairs and armchairs or the springs for a bed, is completed.
However, a critical feature of these items of furniture lies not only in the preparation of the supporting elements, but also when it becomes necessary to replace elements that have broken or deteriorated through time and with use, i.e. during the steps of assembling and disassembling these elements on and from the supporting structure. In fact, the relevant operation is technically difficult and economically costly, so that often it is not worthwhile, even if the supporting structure, equipped with new elements, could still be used for a long time.